The present invention relates generally to methods and apparatuses for detecting cancer and more particularly to a method and apparatus for mapping a tissue sample and for distinguishing different regions thereof based on luminescence measurements of cancer-indicative native fluorophors.
Because a sufficiently effective method has not yet been developed to prevent cancer, cancer research has focused on the most effective ways to treat cancer. As different as the various forms of treatment have been--ranging from excision to radiation to chemotherapy--all treatments have relied on one crucial step, the detection of cancerous tissue. The importance of detection cannot be stressed enough. Early detection not only indicates the presence of a cancer but also may give an indication as to where the cancer originated and what type of treatment will be the most safe and effective. In addition to being used to detect cancer early, detection methods may also be used to determine whether treatment methods have been successful in eradicating cancer from a patient.
At present, methods for detecting cancer have relied primarily on the use of X-rays, nuclear magnetic resonance, nuclear radiation or invasive methods based on chemical laboratory analysis and biopsy.
In U.S. Pat. No. 5,042,494, which is incorporated hereinto by reference, there is disclosed a method and apparatus for detecting the presence of cancerous tissue using native visible luminescence, The tissue to be examined is excited with a beam of light that causes the tissue to fluoresce over a spectrum of wavelengths. The intensity at which the excited tissue fluoresces can be measured either over a spectrum or at a predetermined number of preselected wavelengths. By determining the wavelength(s) at which maximum intensity(ies) are attained for the tissue in question and by comparing these peak wavelengths, either visually or electronically, to the peak wavelength(s) derived from a known non-cancerous tissue, or by comparing the luminescence spectrum of the excited tissue with the luminescence spectrum of a known non-cancerous tissue and/or known cancerous tissue or the excitation spectra of the excited tissue with the excitation spectra of known cancerous and/or known non-cancerous tissue, one can determine the carcinomatoid status of the tissue in question.
In U.S. Pat. No. 5,131,398, which is also incorporated hereinto by reference, there is disclosed a method and apparatus for distinguishing cancerous tumors and tissue from benign tumors and tissue or normal tissue using native fluorescence. The tissue to be examined is excited with a beam of monochromatic light at 300 nanometers (nm). The intensity of the native fluorescence emitted from the tissue is measured at 340 and 440 nm. The ratio of the two intensities is then calculated and used as a basis for determining if the tissue is cancerous as opposed to benign or normal.
Other patents or publications of interest may include Photometrics CCD Newsbrief, Photometrics Ltd., Tuscon, Ariz. (December, 1992); Silicon-Detector Arrays Advance Medical Imaging, Laser Focus World, pp. 139-140 & 142-143 (March, 1993); and a paper entitled "Discrimination and Classification with Xybion Multispectral Video Systems," by Paul A. Frost, presented at the 19th International Congress on High-Speed Photography & Photonics, Cambridge, UK (Sep. 18, 1990), all of which are hereby incorporated by reference.